While insects are able to navigate in turbulent streams to find their mates or food from sparse pheromone or odor detection, even in case of poor space perception for some of them, machines face difficulties in handling such a problem despite the needs e.g., locating drugs, chemical leaks, explosives, and mines. Semiconductor gas-sensors are able to detect the presence or absence of specific odorous substances and to determine their concentration. However, locating the sources has to take into account the environment and particularly the air or liquid flow in which the odorous substance diffuses in a chaotic way.
Most of the robots equipped with an odor sensor use the local concentration gradient of an odorous substance to determine locally the direction of its source, referred to as chemotactic search strategy. However, chemotactic search strategies based on local concentration gradients require concentration to be sufficiently high so that its average difference measured at two nearby locations is larger than typical fluctuations. The signal-to-noise ratio depends of course on the averaging time and might be improved by waiting. However, average concentration may be decaying rapidly e.g., exponentially, with the distance away from the source and in this weak signal-to-noise (dilute) case waiting becomes worse than exploratory motion. As an illustration, FIG. 1 depicts an example of an environment where an odorous substance is diffused within the atmosphere and where odorous substance concentration cannot be used locally to determine the odorous substance source.
Chemotaxis requires a reliable measurement of local gradients. This is not feasible for robots located far away from the source and severely limits the range of application of automated source localization by robots. Existing chemotaxic robots might take several minutes to locate a source a few meters away.
Therefore, there is a need to provide a method and systems for solving the challenge of locating an emitting source, e.g. locating particle or molecule sources or heat sources in a dilute environment, in particular for the design of sniffers or robots that track chemicals emitted by drugs, chemical leaks, explosives and mines.
To solve these issues, there is provided an efficient method, device, and computer program to search for an emitting source in a turbulent flow, lacking space perception and cognitive and/or probabilistic maps.